1. Field of the Invention
This invention relates to a labelling machine for objects, in particular bottles, with several operating stations located behind one another along a track. The operating stations include an adhesive application apparatus, a label supply box and a label transfer cylinder. The machine includes at least one extracting element for the labels which is mounted so that it can rotate on a rotating support and move past the stations during each rotation of the support. The extracting element has an outwardly-curved receptacle surface for the label which rolls along the stations. The drive for each extracting element is a cam drive, which comprises common, stationary double cam discs for all the extracting elements. The cams are located on one side in two planes with one above and at some distance from the other. Two sets of followers are mounted on an extracting element drive shaft or on a bearing shaft coupled with it by means of a support element. The followers cooperate with the two cams to produce positive movement of each extracting element over its entire revolution when the support rotates.
The invention also relates to a support element for the followers of a cam drive mechanism and, more particularly, to a drive mechanism for a label extracting element in a labelling machine.
Still further, the invention relates to a labelling station of a labelling machine for containers, such as bottles, with a support table which can be driven by a central drive shaft. The table support has at least one extracting element which has a curved receptacle and is mounted so that it can rotate in the machine frame. When the table rotates, the extracting element rotates or pivots around its own axis and is moved along a closed track past stations for the application of adhesive to the receptacle surface and for the storage or transfer of the labels. Each extracting element is rotated or pivoted by a cam transmission which, in turn, is moved by a cam disc which is mounted on the machine frame and which is common for all of the extracting elements.
2. Description of the Prior Art
The prior art includes various cam-controlled drive mechanisms to turn the extracting elements in labelling machines at the various stations in the same direction over their entire orbit. The extracting elements may turn at different angular velocities at different locations during the turning thereof.
In one drive system of the prior art as disclosed in German Patent No. 24 36 003 P2, the extracting elements are always driven by a pair of lever arms, which are guided with a follower in a closed grooved cam. The partly-overlapping grooved cams are in different planes for a clear guidance of the lever arms. Because of the guidance of each follower on two flanks of the corresponding grooved cam, each follower is clearly guided. The grooved cams are configured so that the one follower is under torque when the other follower is in an idle position. It does not appear that such a drive mechanism, however, has been realized in actual practice.
Nor, it seems, has it been possible to realize in actual practice another drive mechanism for a labelling machine of the type described in German Patent Publication Published for Opposition Purposes No. 27 09 521 A1. In this latter drive mechanism, there are two cam discs with cams having outside surfaces which are located in two planes, one above the other. For each cam, there is a set of two followers. The two pairs of followers are offset on the upper and lower side of a disc by 90 degrees in relation to one another. The disc is supported by a bearing shaft which extends to the plane between the cam discs. It cannot be determined from the teaching of this prior art device whether precautions have been taken to ensure a collision-free passage of the bearing shaft in the outside radial areas of the cam disc adjacent to the bearing shaft. Still further, the two pairs of followers are located at the same radial distance (same lever arm length) from the bearing shaft of the support element. It also cannot be determined whether particular precautions have been taken for a compact design of the drive mechanism in which there is the most favorable possible distribution of the load on the drive system at the various stations.
A labelling machine of the general type described above has been disclosed in U.S. Pat. No. 4,298,422 and includes another drive mechanism, however, which appears to have been used in actual practice. In this labelling machine, the cam drive mechanism is designed as a lantern gear transmission including two sets of lantern gear teeth which are located on the inside of the double cam disc designed as a ring-shaped body. A support element supports one set of the followers designed as lantern wheels on its two sides and is located between the two lantern gears on the end of the downwardly extending drive shaft of the extracting element. So that a collision-free passage of the drive shaft along the lantern gear on the shaft side is possible, the points of the teeth of the lantern gear are cut off.
With such a drive mechanism, of course, a non-uniform rotation of the extracting elements can be achieved, but the cost and complexity of the lantern gear transmission would be significant. A further disadvantage includes the radial diameter of the lantern gears not being very compact because of the minimum width of the individual teeth.
Existing labelling machines comprise a series of interconnected parts which employ a thin insert of elastic material at the junction of the parts to reduce mechanical noise. Such machines include a labelling station in which an extracting element is employed to apply adhesive to the labels and transfer the labels to containers. The extracting element is driven by means of a lantern gear transmission which includes an annular body having two internal lantern gears and two lantern wheels engaged with the lantern gears which are located on the opposite side of a support and act as followers to damp noise and compensate for part tolerance. See, for example, U.S. Pat. No. 4,298,422 which is incorporated herein by reference as if the entire contents thereof was fully set forth herein.
Each follower is equipped with an insert designed to allow for the damping of noise and compensation of tolerances. The insert is in the form of a bushing interposed between the inner bearing and the outer running surface of a roller, with which each lantern wheel is equipped. The employment of such an insert in a cam drive mechanism is not practical, because of the high load exerted on the rollers, which are mounted on the followers, due to the small surface area of the insert. This is especially true if only a few rollers, for example, two, are employed.
Since the insert is constructed as thin as possible to achieve a precise guidance, large loads can reduce or entirely eliminate the damping action, because the bearing and the running surface come in direct contact with one another. Moreover, any eccentricity which occurs due to load will reduce the desired precise rotational movement of the extracting element.
It is not uncommon for prior art labelling stations, in which the extracting elements are located above a support table and are mounted on a shaft in bearings in the support table, to employ a hollow central shaft through which a central drive shaft runs and on which the table is mounted. The hollow drive shaft and a tension element running through it extend through an opening located in the base plate of the machine frame to below the base plate, where the coupling between the drive and the drive shaft is located. By activating the tension element, the coupling can be axially retracted, so that the drive shaft can be uncoupled from the drive. When uncoupled, the support table can then be realigned by rotating it. Such a realignment is used during format changes of containers or labels to center the labels on the containers. See, for example, German Patent No. 2,435,540 B2, the contents of which are herein incorporated by reference as if set forth fully herein.
Such labelling stations have the disadvantage that a great deal of space is required for the mounting of the table on the hollow shaft of the machine frame. An additional disadvantage is that access to the coupling is located underneath the base plate of the machine frame and is extremely difficult to reach. When adjusting the degree of rotation during realignment it is useful to be able to check the degree of rotation if the service personnel can get to the coupling without a great deal of effort.